Cold hardiness & minimum temperature

Is Turnip 'Purple Top White Globe' (Brassica rapa var. rapa 'Purple Top White Globe')cold hardy? Hardiness zone & min temp

Also called Purple Top White Globe turnip, garden turnip.

More about turnip 'purple top white globe'

About Turnip 'Purple Top White Globe'

Brassica rapa var. rapa 'Purple Top White Globe' · also called Purple Top White Globe turnip, garden turnip · edible

'Purple Top White Globe' is the classic heirloom turnip with smooth white roots flushed bright purple at the shoulder. Fast and reliable, roots reach 8-12 cm and mature in about 50-55 days, sweetening after frost. Both the root and the nutritious greens are eaten. Sow direct in full sun in cool spring or autumn weather.

Cold limit: USDA 2-9 (grown as a cool-season crop) · RHS H4 (10-18°C)

What turnip 'purple top white globe''s hardiness rating actually means

Hardiness works differently for turnip 'purple top white globe': it is grown as a seasonal crop, not overwintered. The question is not "what zone" but "how long is your frost-free growing window". Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 2-9 (grown as a cool-season crop) — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

As an annual crop, its "minimum temperature" is the first hard frost — that is the end of the plant's life, not a survivable low. Many types are also damaged by light frost (around 0 °C).

Concretely, for turnip 'purple top white globe' as it gets too cold:

Light frost (around 0 to −2 °C) damages or kills tender summer crops outright; cold-hardy types take a few degrees of frost.
The plant does not "survive winter" — its life cycle simply ends, by design, when frost arrives or it finishes cropping.
A surprise late spring frost can also kill young transplants set out too early, before the season even starts.

Can turnip 'purple top white globe' go outside or overwinter — and where?

Time it to your frost dates: sow or plant out after the last spring frost, and aim to harvest before the first autumn frost.
In short-season zones, start it indoors or under cover to stretch the effective growing window.
Hardier crops in this group can be sown for an autumn or overwintered harvest in mild zones — check the specific crop.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when turnip 'purple top white globe' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Frost protection for borderline turnip 'purple top white globe'

Turnip 'Purple Top White Globe' is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Use fleece, cloches or a cold frame at each end of the season to dodge a borderline frost and add growing weeks.
Have row cover ready for an unexpected late spring or early autumn frost.
Know your local last- and first-frost dates and count back the crop’s days-to-maturity to schedule the sowing.

Turnip 'Purple Top White Globe' hardiness — frequently asked questions

Is turnip 'purple top white globe' cold hardy?

Hardiness works differently for turnip 'purple top white globe': it is grown as a seasonal crop, not overwintered. The question is not "what zone" but "how long is your frost-free growing window". A seasonal crop, not a perennial. Turnip 'Purple Top White Globe' is grown as an annual in USDA 2-9 (grown as a cool-season crop); you sow after the last frost and harvest before the first one, then start again next year.

What is the minimum temperature turnip 'purple top white globe' can survive?

As an annual crop, its "minimum temperature" is the first hard frost — that is the end of the plant's life, not a survivable low. Many types are also damaged by light frost (around 0 °C).

What hardiness zone is turnip 'purple top white globe'?

Turnip 'Purple Top White Globe' is rated USDA 2-9 (grown as a cool-season crop) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can turnip 'purple top white globe' survive winter outside?

Time it to your frost dates: sow or plant out after the last spring frost, and aim to harvest before the first autumn frost. In short-season zones, start it indoors or under cover to stretch the effective growing window. Hardier crops in this group can be sown for an autumn or overwintered harvest in mild zones — check the specific crop.

How do I protect turnip 'purple top white globe' from frost?

Use fleece, cloches or a cold frame at each end of the season to dodge a borderline frost and add growing weeks. Have row cover ready for an unexpected late spring or early autumn frost. Know your local last- and first-frost dates and count back the crop’s days-to-maturity to schedule the sowing.